Timothy P. Cahill’s former campaign manager was acquitted of corruption charges Tuesday, but the jury said it was deadlocked on the charges against Cahill, leaving the former treasurer’s fate in limbo as deliberations stretch into a seventh day.

The jury’s announcement that it had cleared Scott Campbell of two counts of conspiracy but was still wrestling with the same charges against Cahill added a new element of suspense to the trial, which ­began five weeks ago.

After Campbell was cleared, Judge Christine Roach gave the jurors, who have deliberated for 38 hours since Dec. 4, what lawyers call the “dynamite’’ charge, urging them to try once again to reach a verdict in Cahill’s case. Such a charge is usually the last step taken before a mistrial is declared due to a hung jury. In that case, prosecutors would have to decide whether to retry Cahill.

Jurors, many of whom looked weary by day’s end on Tuesday, will return to Suffolk Superior Court for further ­deliberations on Wednesday.

A mistrial would be a major blow to Attorney General ­Martha Coakley, who has ­alleged that both Cahill and Campbell participated in a scheme to use a $1.5 million, publicly funded lottery ad blitz to boost Cahill’s flailing campaign for governor in 2010.

Coakley charged both men under a 2009 state ethics law that was passed in response to the corruption scandal involving former House speaker ­Salvatore F. DiMasi.

The law changed many ethical breaches that had been classified as civil violations, punishable with fines, into criminal ­violations, punishable with prison time.

But the case against Cahill and Campbell is the first significant test of the law, and prosecutors have to show that both men not only misused the lottery ads, but intended to exploit them for Cahill’s political gain.

In Campbell’s case, they failed. And in Cahill’s case, the jury appears to be struggling.

“They have a high bar in this case to show there was fraudulent intent, and that may be why the jury is deliberating so long,” said Pamela Wilmot, ­executive director of Common Cause Massachusetts. The evidence, she said, “has to be pretty strong to get to that level.”

The prosecution’s case centers around a trail of e-mails, text messages, and phone ­records that allegedly show that Cahill’s political operatives discussing the timing and content of lottery ads with executives at Hill Holliday, the Boston agency that was being paid state money to handle the lottery’s ad account.

Cahill has argued that his only interest in pushing for the ads was to rebuild the image of the lottery, which he said had been tarnished by attack ads run by the Republican Governors Association.

Campbell’s lawyer argued that his client was a “flunky,” passing e-mails about the ads on to Cahill, without participating in any plot to use them for Cahill’s political benefit.

Jurors have asked Roach three questions about the case this week. But the questions have not been disclosed; the judge has sent private written responses to the jury after discussing them in a sidebar with prosecutors and defense lawyers.

Roach did not explain why the questions, which are typically revealed in open court, were kept secret.

On Tuesday, the Globe filed a motion asking the judge to ­divulge the contents of the questions and her answers. Roach has not responded to the motion.

Often, jury questions involve requests for clarification about the law. Lawyers say that, in rare cases, judges can keep the questions secret if they involve a juror’s personal life.

Whatever the questions were, they did not affect the verdict for Campbell. His acquit­tal delivered an emotional jolt to his relatives and supporters, who had been anxiously waiting in the courtroom with Cahill’s relatives since jury deliberations began last week.

Campbell was a longtime Cahill associate who worked for him for years in the Treasury Department before becoming Cahill’s campaign manager in 2010. But Campbell’s lawyer ­argued that the two men were not on equal footing and that Cahill’s treatment of Campbell “bordered on abuse.”

In court, both men avoided talking to or making eye contact with one another as they sat at each end of the ­defense table.

But after the jury ­announced that Campbell had been cleared, Cahill stood up and patted his former aide on the shoulder.

Campbell said he told his former boss, “Good luck.”

“I’m very happy,” Campbell said as he left the courtroom, surrounded by his wife and relatives. “I’m very relieved. We’re ready to move on. Thank you to the jury.”

Cahill later said: “I’m very happy for Scott.”

His lawyers declined to comment on Campbell’s acquittal. Cahill’s wife, Tina, said it gave her hope that her husband would be cleared, as well.

Jim O’Brien — the chief of Coakley’s Public Integrity Division, who prosecuted Campbell and Cahill in court — declined to comment.

Despite the acquittal, ­Campbell’s legal ordeal is not over yet.

He faces unrelated charges stemming from the patronage scandal in the state’s Probation Department.

Prosecutors allege that in that case, Campbell concealed the identity of donors to Cahill’s campaign, as part of a scheme to get the probation commissioner’s wife a job at the state lottery.